During the early stages of periodontal disease, known commonly as gingivitis, bacteria on the teeth and near the gingiva infect and irritate the sulcus where the gingiva approximates the tooth. The presence of bacteria can lead to destruction of the gingival epithelium which connects the gingiva to the tooth and can force the epithelium to separate from the root of the tooth. Also, as a result of bacterial presence, inflammatory cells increasingly populate the gingival tissues. Thus, the tissue is weaker due to the disease, and attachment is lessened. Of course, further infection moves the tissue attachment further toward the apex of the tooth, creating a pathological pocket much deeper than the normal sulcus.
Naturally, this pocket is difficult to clean or floss because the routine cleaning instruments of normal home care cannot reach the bacteria or plaque, which accumulate within the pocket. As disease extends the pocket, the periodontal ligament which attaches the tooth to the supporting bone, and the supporting alveolar bone itself, are destroyed. This disease leaves a periodontal defect, filled with plaque and bacteria. Ultimately, the tooth could be surrounded by loose, diseased, and detached gingiva. Eventually such deterioration can result in the loss of the tooth.
One conventional treatment of periodontal defects involves surgically gaining access to the tooth root surface in an effort to remove bacteria and possible infected soft tissue and to alter the periodontal pocket or obtain reattachment of the connective tissue toward the crown of the tooth. Some of the former methods accomplish this attachment by cutting away gingival tissue near the crown of the tooth and, if necessary, shaping underlying bone to create a sulcus similar in depth to a normal sulcus so that regular oral hygiene may be used to maintain attachment of the gingiva to the tooth. Of course, such treatment does not recreate the attachment of the gingiva near the crown like that which existed before any diseased condition. Such treatment also does not replace any periodontium lost to disease.
Another conventional surgical treatment for periodontal disease is known as a gingival flap procedure. One or more flaps of gingival tissue are retracted from the tooth. After the tooth root is thoroughly cleaned, and diseased soft tissue is removed, these flaps are reopposed to the tooth. In some instances gingival grafts from other portions of the mouth are incorporated. Reattachment is unpredictable using this procedure. This is because gingival epithelium migrates rapidly along a tooth root toward the apex of the tooth, and bone cementum, and periodontal ligament migrate much more slowly. If the gingival epithelium is allowed to migrate toward the base of the periodontal defect, the gingival tissue is said to undergo a process called repair. The more desired process would allow the bone, cementum, and periodontal ligament cells to migrate coronally; this process is called regeneration. Repair is simply healing but regeneration is healing of the defect with the return of the defect towards the original condition.
Typically, after periodontal surgery, a race begins among the cells from the four types of periodontal tissues, gingival epithelium, gingival connective tissue, alveolar bone and periodontal ligament, to repopulate the previously diseased root surface.
If uncontrolled, the healing process usually results in downgrowth of cells from the gingival epithelium along the surface of the gingival connective tissue immediately lateral to the root surface, which prevents migration of cementoblasts from the adjacent periodontal ligament to form new cementum on the denuded root surface to which new periodontal fibers can attach. Even if the gingival connective tissue, also quick to take part in the healing process, occupies the space immediately lateral to the root surface and hinders the downgrowth of epithelial cells, there will be no true new attachment between that type of tissue and the root surface but rather a substantial risk of root resorption.
If the alveolar bone, which usually regenerates more slowly than the gingival epithelium and connective tissue, happens to fill up parts of the space adjacent to the root surface and reaches the root surface, the bone will form an ancylotic union with the part of the root which is unprotected by root cementum and periodontal ligament tissue.
If, on the other hand, cement-producing cells, e.g., cementoblasts from the remaining adjacent and intact periodontal ligament tissue, reach the denuded root surface area, they will desirably produce cementum with inserting connective tissue fibers on the dentine surface, e.g., a true, new periodontal ligament is formed uniting the root with the surrounding bone and gingival connective tissue.
Unfortunately, the cementoblasts do not normally reach more than a negligible part of the previously diseased root surface immediately adjacent to the intact periodontal ligament due to the fact that cells of the other tissues (e.g., gingival epithelium, gingival connective tissue, soft tissue, etc.) occupy the wound area.
Therefore, there is a need for devices and methods that utilize guided tissue regeneration where the cementum and periodontal ligament producing cells have the ability to become established on the root surface by maintaining space and isolating the root surface from other tissues during healing. This isolation during the initial healing process will reduce migration of gingival epithelium and enable the periodontal ligament to become re-established in a proper sequence resulting in a new periodontal attachment.